White porcelain streak plates are great for testing minerals. Often, the color of the

mineral's streak is a clue as to the identification of the mineral. The streak
is the color of the mineral in powder form. To perform the test, rub the
mineral on the plate and observe the color. Many minerals have a streak that is
the same as their outward appearance; however, some streaks are very different
colors! Each streak plate is 2” x 2”.